Deprecated function add_option_whitelist

Came here to report the same thing. Classic Editor plugin (v1.5) is producing the following error on 5.5-beta2:

Deprecated: add_option_whitelist is deprecated since version 5.5.0! Use add_allowed_options() instead. in /Users…/wp-includes/functions.php on line 4767

add_option_whitelist() is being called at line 339 in classic-editor.php

I’ve just raised this as an issue over on the Github repo

https://github.com/WordPress/classic-editor/issues/124

Just got notice on the above Github issue that I raised that this has been fixed in a future update…

The notice was fixed some time ago and will be in the plugin update for WP 5.5.

Fixed with #123.